Urinary incontinence (UI), as defined by the International Continence Society, is “the complaint of any involuntary leakage of urine.” The most common type of urinary incontinence in women is stress urinary incontinence (SUI), followed by urge and mixed incontinence. Urinary incontinence is not a life-threatening or dangerous condition, but it is socially embarrassing and may cause withdrawal from social situations and reduced quality of life. An estimated 80% of people affected are women. Urinary incontinence is believed to affect at least 13 million people in the United States, and is expected to increase sharply with the aging of the baby boomers.
A variety of approaches have been designed to diagnose the cause of SUI. The most widely used method is urodynamics to measure storage and voiding functions of the urinary bladder and the urethra. Urodynamic testing normally consists of two main phases: 1) filling cystometry to investigate storage of urine in the bladder, including ability to store without leakage during provocative maneuvers such as coughs and in-spot jogging, and 2) followed by a pressure-flow measurement to examine urine voiding performance. During these tests, a thin, flexible catheter, called a Foley catheter, is inserted into the bladder through the urethra, and residual bladder volume is measured followed by the performance of filling, provocative and voiding studies. More sophisticated testing uses an intravaginal or peri-anal electrode to measure the electrical activity of the pelvic floor muscles. Further ambulatory urodynamic studies with natural filling are also applied for patients to avoid the unnatural environment of the urodynamic clinic. Ambulatory studies have been found useful for confirming overactive detrusor muscle activity in patients for whom conventional urodynamic tests failed to reproduce symptoms.